It has been known that an organic polymer comprising at least one reactive silicon-containing group in one molecule has a property of crosslinking by siloxane bond formation accompanied with, for example, hydrolysis of a reactive silicon group due to water etc. at a room temperature and accordingly giving a rubber-like cured product.
With respect to the reactive silicon group-containing polymer, a polymer having a polyoxyalkylene main chain or a polyisobutylene main chain are disclosed in Patent Document 1, Patent Document 2 and the like and have already been produced industrially and used widely for uses as a sealant, an adhesive, paint and the like.
The curable composition comprising an organic polymer having a reactive silicon group is cured using a silanol condensation catalyst and, generally, an organotin catalyst having a carbon-tin bond, such as dibutyltin bis(acetylacetonate), is widely used. However, in recent years, issues have been raised concerning the toxic features of organotin compounds and, therefore, the development of non-organotin catalysts has been awaited. In Patent Document 3, Patent Document 4, Patent Document 5, Patent Document 6 and Patent Document 7, there are disclosed tin carboxylate salts and other metal carboxylates salts as silanol condensation catalysts and, further, it is disclosed that the addition of an amine compound as a cocatalyst or promoter results in improved curability. Further, from the environmental stress viewpoint, substantially metal-free curing catalysts are favorable and Patent Document 8 discloses that metal-free silanol condensation catalysts can be obtained by using an amine compound and a carboxylic acid in combination. In spite of the fact that it is known that the combined use of an amino compound with another silanol condensation catalyst results in improved curability, as mentioned above, there are disclosed few catalyst systems in which an amine compound is used alone as a silanol condensation catalyst. Further, the use of the non-organotin catalysts described in the patent documents cited above raises the problem that the adhesiveness tend to be inferior as compared with the use of organotin catalysts.
Patent Document 9 discloses the technology of using amine compounds known in the art as silanol condensation catalysts, specifically mentioning DBU (1,8-diazabicyclo[5.4.0]undec-7-ene and the like.
The present inventors used such amine compounds as described in the above-cited Patent Document 9, for example DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), as silanol condensation catalysts for reactive silyl group-containing organic polymers and encountered a problem: namely, no practical curability can be obtained in some instances. Further, they increased the levels of addition of amine compounds to thereby secure practical levels of curability, upon which they encountered another problem: the adhesiveness of the resulting curable compositions can hardly be secured.    Patent Document 1: Japanese Kokai Publication Sho-52-73998    Patent Document 2: Japanese Kokai Publication Sho-63-6041    Patent Document 3: Japanese Kokai Publication Hei-5-39428    Patent Document 4: Japanese Kokai Publication Hei-9-12860    Patent Document 5: Japanese Kokai Publication 2000-313814    Patent Document 6: Japanese Kokai Publication 2000-345054    Patent Document 7: Japanese Kokai Publication 2003-206410    Patent Document 8: Japanese Kokai Publication Hei-5-117519    Patent Document 9: International Publication WO2004/022618